Abstract

First-principles calculations are performed to investigate the dissolving, trapping and detrapping of H in six bcc (V, Nb,Ta, Cr, Mo, W) and six fcc (Ni, Pd, Pt, Cu,Ag,Au) metals. We find that the zero-point vibrations do not change the site-preference order of H at interstitial sites in these metals except Pt. One vacancy could trap a maximum of 4 H atoms in Au and Pt, 6 H atoms in V, Nb,Ta, Cr, Ni, Pd, Cu and Ag, and 12 H atoms in Mo and W. The zero-point vibrations never change the maximum number of H atoms trapped in a single vacancy in these metals. By calculating the formation energy of vacancy-H (Vac-Hn) complex, the superabundant vacancy in V, Nb,Ta, Pd and Ni is demonstrated to be much more easily formed than in the other metals, which has been found in many metals including Pd, Ni and Nb experimentally. Besides, we find that it is most energetically favorable to form Vac-H1 complex in Pt, Cu,Ag and Au, Vac-H4 in Cr, Mo and W, and Vac-H6 in V, Nb,Ta, Pd and Ni. At last, we examine the detrapping behaviors of H atoms in a single vacancy and find that with the heating rate of 10 K/min a vacancy could accommodate 4, 5 and 6 H atoms in Cr, Mo and W at room temperature, respectively. The detrapping temperatures of all H atoms in a single vacancy in V, Nb,Ta,Ni, Pd, Cu and Ag are below room temperature.

Received 26 September 2012Accepted 11 January 2013Published online 18 January 2013

Acknowledgments:

This work was supported by the National Magnetic Confinement Fusion Program (Grant No.: 2011GB108004), the National Natural Science Foundation of China (Nos.: 91026002, 91126002) and the Strategic Priority Research Program of Chinese Academy of Sciences (Grant No.: XDA03010303), and by the Center for Computation Science, Hefei Institutes of Physical Sciences.

Article outline:I. INTRODUCTIONII. METHODOLOGYIII. RESULTS AND DISCUSSIONA. Occupancy properties of one H atom in bcc and fcc metals1. One H atom in bcc metals2. One H atom in fcc metalsB. Multiple H atoms accumulation in a single vacancy1. Accumulation of multiple H atoms in a single vacancy in bcc metals2. Formation of SAV in bcc metals3. Accommodation of multiple H atoms in a single vacancy in fcc metals4. Formation of SAV in fcc metalsC. Detrapping of H atoms in a single vacancyD. Issues and challengeIV. CONCLUSION

Abstract

First-principles calculations are performed to investigate the dissolving, trapping and detrapping of H in six bcc (V, Nb,Ta, Cr, Mo, W) and six fcc (Ni, Pd, Pt, Cu,Ag,Au) metals. We find that the zero-point vibrations do not change the site-preference order of H at interstitial sites in these metals except Pt. One vacancy could trap a maximum of 4 H atoms in Au and Pt, 6 H atoms in V, Nb,Ta, Cr, Ni, Pd, Cu and Ag, and 12 H atoms in Mo and W. The zero-point vibrations never change the maximum number of H atoms trapped in a single vacancy in these metals. By calculating the formation energy of vacancy-H (Vac-Hn) complex, the superabundant vacancy in V, Nb,Ta, Pd and Ni is demonstrated to be much more easily formed than in the other metals, which has been found in many metals including Pd, Ni and Nb experimentally. Besides, we find that it is most energetically favorable to form Vac-H1 complex in Pt, Cu,Ag and Au, Vac-H4 in Cr, Mo and W, and Vac-H6 in V, Nb,Ta, Pd and Ni. At last, we examine the detrapping behaviors of H atoms in a single vacancy and find that with the heating rate of 10 K/min a vacancy could accommodate 4, 5 and 6 H atoms in Cr, Mo and W at room temperature, respectively. The detrapping temperatures of all H atoms in a single vacancy in V, Nb,Ta,Ni, Pd, Cu and Ag are below room temperature.

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Dissolving, trapping and detrapping mechanisms of hydrogen in bcc and fcc transition metals